1. Technical Field
The present invention relates to routing protocols and communication systems adapted for use with vehicles, and more particularly to an improved protocol and system configured to forward a communication towards a destination through inter-vehicular transmission, and without the use of a map database.
2. Background Art
Vehicular communication systems have been developed to inform targeted groups of vehicles of events or conditions deemed relevant to a particular group. Often, these groups can be categorized within one of a plurality of classes including opposite traffic approaching the condition, and same-way traffic approaching the condition. These conventional systems typically rely upon a traffic information center operable to transmit an alert of the condition to the targeted group, and at least one probe vehicle operable to transmit notification of the condition to the center. Alternatively, inter-vehicular communications amongst probe vehicles have also been developed in vehicle-to-vehicle (V2V) enabled environments, wherein the communications are transmitted directly between vehicles. To target directional traffic, both types of systems, as well as combinations thereof, must distinguish approaching versus departing traffic, and opposite versus same-way traffic.
To accomplish this task, both of these systems utilize a map database that cooperates with a locator sub-system to determine the locations and headings of the target group vehicles and the probe vehicle. For example, where a potentially targeted vehicle and the probe vehicle are located on opposite sides of a thoroughfare, according to the map database and locator sub-system, opposite headings are assumed, and whether the remote vehicle is approaching the probe vehicle is determinable by their absolute positions upon the map.
However, the requirement of a map database, typically at the probe vehicle and center, presents operational and scalability concerns. First, maintaining and updating a map database, so as to assure its accuracy, results in significant expenditures including labor costs. Storage requirements at the probe vehicle and center to store the often voluminous database further require increased system capacity and hardware. Finally, the amount of data required to be communicated and processed in real-time at the center is also increased by the transmission and management of the map database. As additional vehicles are added to these systems, these concerns proportionally increase.